Expanding Earth

The expansion theory of the earth (also called expansion hypothesis) is a technology developed in the late 19th century and discussed particularly in the 1950s and 1960s theory that postulated by Alfred Wegener continental drift and the breakup of the supercontinent Pangaea by a permanent increase in the radius of the Earth trying to explain. The most important representatives of German geoscientists Ott Christoph Hilgenberg, the Hungarian geophysicist Laszlo Egyed and Australian geologist Samuel Warren Carey apply.

The theory is no longer represented in the scientific and academic environment, since plate tectonics can explain the Earth's mantle, the movement of the continents on the basis of convection. Meanwhile, accurate measurements of the Earth are possible. They show that at present there is no expansion.

• 2.1 Origin of Continents and Oceans

History and attempts to justify

Expansion at constant mass

Roberto Mantovani published in 1889 and 1909 a theory of Earth expansion. He assumed that a closed continent covered the entire surface was then a much smaller earth. Through volcanic activity due to thermal expansion this continent broke apart, with the newly formed continents away from each other ever since the elevation zones continually expanded and now make up the area of the oceans. Wegener saw similarities with his own theory of continental drift and Mantovani recognized as one of his predecessors, but he did not mention Mantovani Erdexpansionshypothese.

A compromise between the Earth expansion and Erdkontraktion represents the " theory of thermal cycles " by John Joly and Arthur Holmes Measurement with a surplus of internal heat production, if it exceeds by radioactive processes, the extent of natural cooling, creates a kind of heat. It is believed that the formation of columns during the conditional through the heat storage volume increase of the earth's crust. In these columns magma penetrates and reaches the earth's surface as lava partially. The associated heat release occurs after the period of warm-up and expansion, a phase of cooling and shrinkage. These phases are formed according to this theory, a continuous sequence in the Earth's history.

In contrast, Lindemann took (1927 ), Halm (1935 ), László Egyed (1956 ), and Hugh Gwyn Owen ( 1983), an expansion due to phase transitions in the Earth's core to. The core had thus consisted of a super-dense material that transforms into a less dense form and expands it. Egyed conjoining his theory with a possible decrease of the gravitational constant.

However, based on thermal expansion theory is at odds with the most modern principles of rheology; an accepted explanation for the required phase transitions is also missing. As A. D. Stewart noted, a smaller radius of the earth with the same mass would mean that due to the law of gravitation in the past, the force of gravity at the surface was 4 times as large as today. This is to bring the size of the then living dinosaurs only consistent if it is assumed that they lived in the water.

Expansion due to mass increase

Ivan Ossipowitsch Jarkowski struck in 1888 in connection with his mechanical explanation of gravitation a kind of absorption of the ether before, which would transformed into the heavenly bodies in new chemical elements, thus causing an expansion of the heavenly bodies. However, he does not mention the connection with the formation of the continents. The first comprehensive work on the expansion of the earth with the title "From growing globe " published in 1933 Ott Christoph Hilgenberg. He had made ​​an attempt to accommodate the continents on a globe of smaller diameter as completely as possible and tended to think that the ocean basins had formed only by an expansion, the expansion of the Earth.

The best known representative of the model Earth expansion, Samuel Warren Carey, suggested recently as 1996, also an increase in mass before, but curtailed that a real solution of the problem can be achieved only at cosmological level in connection with the expansion of the universe. As Carey notes, this model is at least not affected by the criticism Stewart: Because if in addition to the radius and the mass of the Earth in the past was small, these effects and the gravity at the surface compensate remains at least approximately constant and the effect the lower mass increases, the force of gravity would previously have been even lower, which could explain the size of the dinosaurs, according to Carey.

However, any ( undefined ) emergence of new matter by absorption of an ( unexplained or debilitated ) ether model according to the prevailing opinion is regarded as one of the modern physics incompatible speculation. The only accepted by modern physics object that is an ether model at least reasonably close to those neutrinos.

Decrease of the gravitational constant

This hypothesis arose from the conjecture of Paul Dirac ( around 1938 ) that the gravitational constant decreases slowly in geological times. This led Pascual Jordan in 1964 to postulate a true for all planets expansion. In contrast to other models of explanation, this hypothesis has been classified at least in the context of physics as absolutely possible. Max Born Jordan describes modification of the gravitational constant as a " systematic generalization " of the general theory of relativity of Einstein.

This hypothesis causes such as the theories with constant mass return problems in relation to the existence of dinosaurs. The gravity would be on the surface, not only because of the smaller radius, but also because of the higher gravitational constant is much larger than today, and here are some dinosaur species would have collapsed under its own weight. Main objection to this theory is that recent measurements of a possible variation of the gravitational constant showed an upper limit for a relative change of only 5 • 10-12. This is a lower value by the factor 10, than need it Jordan for his theory.

Earth expansion and subduction

Origin of continents and oceans

Supercontinent: After the earth was created, is a supercontinent that existed, which has the surface of the earth practically completely covered. Due to the increase of the earth's crust is Erdvolumens, torn at their weakest points, where now are the oceans and so have led to the emergence of the continents. As according to the established theory of plate tectonics new ocean floor is created here by seafloor spreading at mid-ocean ridges. In the expansion theory of compensating missing through the process of subduction, falls through the ancient crust, the formation of new crust thus compensates and makes a constant radius possible. The existence of subduction, it is now, which is mainly criticized in this context by the followers of Earth expansion as Hilgenberg or Carey. An exception is, for example, Owen, who combines the Earth expansion with plate tectonic processes such as subduction.

Shape of the continents: The main argument for the Earth expansion is cited by proponents that if today's oceans are removed and then the Earth's radius is reduced, the continents supposedly better fit each other given its greater curvature, at the on Wegener following as it reconstructions of the supercontinent Pangaea is the case with a constant radius. Most of the representatives it an ideal radius of about 50-60 % of the current value in the Mesozoic is assumed 250 million years ago. It is generally agreed that the emergence of mid-ocean ridges began towards the end of the Permian and the Mesozoic and even in the Pacific Ocean. Therefore, in contrast to the theory of plate tectonics also a coincidence of the contours in the opposite Pacific coasts is postulated, for which various models have been proposed. An exception here is again Owen, who assumes a radius of 80 % of today's value, a match of the Pacific coast is not provided to him.

Orogeny: Following Some models of German and Italian geologists of the 19th century declared Carey the orogeny as a result of upgrades of lighter rock areas ( diapir ) due to the interplay of gravity, thermal expansion and phase transitions. In contrast, the theory of plate tectonics explains the formation of fold mountains with the material build-up under the horizontal applied pressure on each other zubewegender tectonic plates. A distinctive speaking for plate tectonics example is the Indian subcontinent, which broke away from Africa and shifted through the hazards arising from the Hindu-Arabic back broadening of the ocean floor to the northeast, to the Indian plate, the Tethys could disappear here and pushed up with pressure to Asia was whereby the Himalayas was piled.

Development of the oceans: Stewart stated that at a reduction of the radius of the earth in half of the entire planet was covered by an ocean with a depth of at least 8 km, provided that the amount of water corresponds to the current value. During expansion the continents of this primeval ocean then would have arisen, where the water has collected in the elevation and expansion zones, which form the present-day oceans. Carey, however, negated the existence of a global primal ocean and proposed instead that the components of the water together with the new matter come to the surface in a gaseous state in the development of ocean floors and only then add the water of the oceans. Oceanic crust is much younger compared with the continental crust. The oldest oceanic crusts are more than 280 million years old (except on continents deferred oceanic crust, known as ophiolites ), while the continental crust are up to 4.2 billion years old. As the oceanic crust have a smaller thickness than the continental and cracks form at the weak spots, the young age of the oceanic lithosphere is explained by this theory by a complete reformation of the ocean floor during the last 300 million years. The theory of plate tectonics, however, explains the young age of the oceanic lithosphere as a result of a cycle between formation and subduction, which it already existed for at least 3.8 billion years.

Rate of expansion: Some like Jordan or Egyed came from an even, slow expansion. Egyed gave it to the annual increase of the radius of the Earth at about 0.5 to 1 mm, the expansion began already during the formation of the Earth. However, it was criticized that this expansion rate is much too low to explain the shift of the continents since the Mesozoic era before about 250 million years ago, when Pangaea broke up. That's why Owen also refers subduction in his model, which on the one hand holds the expansion rate is low, but on the other hand to guarantee a satisfactory pace of continental drift. Carey, however, rejects the subduction complete and therefore assumes a rapid expansion. This raises, however, the question of why the Pangaea broke only in the Mesozoic and what happened in the billions of years ago. He added because of his hypothesis with the assumption that the expansion at the beginning was relatively slow, with time is the rate of expansion, however, has grown exponentially. However, a reason for this acceleration, he could not specify.

Refutations of Earth expansion

• Wu et al. led in 2011 a precision measurement of the International Terrestrial Reference Frame (using Satellite Laser Ranging, Very Long Baseline Interferometry, Global Positioning System, and Doppler Orbitography and Radio Positioning Integrated by Satellite ) by and combined this with data of the Gravity Recovery And Climate Experiment. This showed that in recent years the maximum annual increase in the radius of the earth was not more than 0.2 mm, which means within the measurement accuracy that during this period no expansion has taken place.

• Williams ( 2000) has studies the moment of inertia of the earth out may have taken place after which no significant change in the radius of the earth in the last 620 million years, and thus the Earth expansion is not tenable.

Since 1970 a large number of references were found in the context of structural geology, seismology, petrology and isotope geochemistry, that the process of subduction is actually taking place. This includes an expansion, not from principle, but by a constancy of the Earth's radius is much more likely. Observations, which are taken as convincing evidence for the occurrence of subduction, are as follows:

• The existence of Wadati - Benioff zones, which are formed by the subducting plates at subduction.
• Created by seismic tomography 3D models of the mantle show cold zones of sinking material exactly in the regions where plate tectonics predicts the decrease in the Earth's crust into the mantle.
• Petrological study of rocks from mountain ranges indicate that these often come from very deep places, this vertical movement can be explained by the interplay of subduction and autopsy. The existence of eclogite in the mountains shows that rock was pushed deep into the mantle, which can be explained by the so-called "slab -pull" force at the mid-ocean ridge in the context of plate tectonics.
• The existence of large shear zones ( suture ) in most mountain ranges. Paleomagnetic and mineralogical studies show that rocks are adjacent, which were originally thousands of miles away. In other words, a part of the crust is missing. The structural geology shows that these missing parts of the crust are not directly below the shear zones. Instead, they have apparently moved along the suture in the mantle. That's a sure indication of the existence of continental collision and subduction of.
• Rare earth metals from volcanic rocks which are formed above subduction zones correspond to the sediments at the head of the subduction plate subject.

Status of the theory

Although still advocated by some researchers outside the scientific mainstream, is now generally considered that the Erdexpansionskonzept is wrong. A current Earth expansion could not be verified experimentally, as was still not an acceptable mechanism to explain the expansion to be created. The theory, neither the numerous processes of Geodynamics still made ​​by the different disciplines of geology (eg tectonics, paleomagnetism, historical geology) collated evidence on the paleogeography of the earth and the determined by seismic image of the crust and uppermost mantle explain. These facts, together with the further development of the theory of subduction, leading to the disappearance of the theory from the current scientific discussion.